Early gene expression profiles during intraoperative myocardial ischemia-reperfusion in cardiac surgery

Hierarchical clustering depicting expression profiles of differentially regulated genes (n = 81) during repair of VSD. Samples shown on the right-hand side were acquired: (1) immediately after cardiac arrest; (2) 50 minutes following cardiac arrest; and (3) 5 minutes after reperfusion prior to right atrial closure. Unsupervised samplewise expression profiles shown on left side are highly coherent within each experimental time point. Unsupervised clustering profile of the 81 significant genes clusters is depicted above the dendrogram. Blue and red depict down- and up-regulation, respectively. VSD, ventricular septal defect.

qPCR versus microarray. There was a high degree of correlation in expression levels of 5 genes differentially regulated during I/R as determined by qPCR and microarray analysis. The prime points for sample measurements are indicated on the X-axis: (1) immediately postcardioplegic arrest; (2) end ischemia; and (3) 5-minute reperfusion. Among the 5 genes sampled, the fold changes in expression were directionally the same as determined by qPCR and microarray at end- I/R compared with baseline in 9 of 10 measurements. Correlation coefficient, based on median R² slope of linear fit of per gene fold changes, measured by qPCR versus microarray = .86; P < .05. IGF1, Insulin-like growth factor-1; Egr-1, early growth response-1; IGFBP-1, insulin-like growth factor binding protein-1; DUSP-1, dual-specificity phosphatase-1; HBA1, α-hemoglobin.

Network map showing common targets of those genes that showed significant up-regulation during reperfusion. Common targets were identified as those genes or proteins subject to upstream regulation, based on available PubMed citations, by at least 2 of the genes or corresponding proteins that exhibited significantly increased expression during reperfusion. Each node in the network map is linked to an html page showing the protein annotation based on available public databases. Small square boxes connecting 2 nodes are linked to an html page showing the type of effect (positive or negative) and the supporting Medline references. Nodes corresponding to genes/proteins that exhibited significantly increased expression during reperfusion are shown in red. Target genes or proteins subject to regulation by genes that exhibited induction during reperfusion are color-coded to reflect functional annotation as growth factors (pink), transcription factors (blue), PI3K signaling (purple), and miscellaneous function (gray).